Methylbenzyl Naphthalene: Liquid Organic Hydrogen Carrier for Facile Hydrogen Storage and Release

A newhomocyclic methylbenzyl naphthalene (MBN) compoundhas beendeveloped as a novel liquid organic hydrogen carrier (LOHC) mediumwith a high gravimetric hydrogen storage capacity of 6.44 wt % andgood dehydrogenation ability. According to the results of theoreticalcalculations of designed MBN, MBN media possesses one of the lowestdehydrogenation enthalpies (<56 kJ mol(H2) (-1)) among homocyclic LOHC media. The Friedel-Craft alkylationreaction allows the formation of an MBN regioisomeric mixture, whichminimizes the production cost for practical applications. This mixtureexists as a liquid with a high boiling point (>623 K) at ambienttemperature.The H-2 storage efficiency of MBN was optimized to achievea yield of greater than 99% using a new Ru-based catalyst. The reactionmonitoring study suggests the stepwise hydrogenation reaction of aromaticrings, which allows the proposed hydrogenation mechanism. The extractionof H-2 from hydrogen-rich H16-MBN wasconducted via a dehydrogenation reaction (yield > 99%) using aPt/CeO2 catalyst, which enabled fast H-2 release.The fasterand facile dehydrogenation of MBN compared to the other reported homocyclicLOHC media coincides with the theoretical calculation results. A novel homocyclic liquid organic hydrogencarrier basedon methylbenzyl naphthalene isomers is employed as a rechargeablehydrogen storage system.